99mTc-反义寡聚核苷酸DNA肿瘤显像的实验研究

拟探讨放射性标记反义寡聚核苷酸(Antisense oligonucleotide,ASON)DNA在荷瘤裸鼠体内显像的可行性。采用两种不同肿瘤细胞系KB-G2和KB-31,并肿瘤内注射的方法;设立ASON的对照正义寡聚核苷酸(Sense oligonucleotide,SON);用聚丙烯酰胺凝胶电泳鉴定所用经MAG3偶联的寡聚核苷酸的杂交活性;完成99mTc-MAG3-ASON和99mTc-MAG3-SON DNA肿瘤内注射后在荷瘤裸鼠体内的显像及其生物分布研究。经MAG3偶联的寡聚核苷酸与天然寡聚核苷酸具有相同的杂交活性。在荷KB-G2瘤裸鼠肿瘤内,99mTc-MAG3-ASON DNA的分布明显高于其对照99mTc-MAG3-SON DNA的分布(14.7vs8.5%ID/g)。但在荷KB-31瘤裸鼠肿瘤内,两者的分布无显著性差异(8.6vs4.3%ID/g)。全身显像显示99mTc-MAG3-ASON DNA较其对照正义DNA寡聚核苷酸在荷KB-G2瘤裸鼠肿瘤内的靶向分布增高,但在荷KB-31瘤裸鼠肿瘤内的靶向分布则未见显著性差异。结果表明:99mTc-MAG3-ASON DNA较其对照正义DNA寡聚核苷酸在荷瘤裸鼠肿瘤内的分布有显著性统计学差异,本研究证实了活体动物体内肿瘤反义显像的可行性。

Experimental Study of 99mTc-antisense DNA for Tumor Imaging

This study was performed to explore the feasibility of antisense imaging with radiolabeled antisense oligonucleotides DNA in tumored nude mice in vivo. Two different tumor cell lines, KB-G2 and KB-31,were used; both antisense and control sense DNAs were administrated intratumorally. The hybridization activities analysis of MAG3 conjugated DNAs oligonucleotides was demonstrated by Polyacrylamide Gel Electrophoresis. The whole body imaging was performed 22 h after administration of radiolabeled antisense and control sense DNAs at 1.0 microg DNAs (100 microCi) in 100 microl per animal. Then the animals were sacrificed at 24 h after administration and the organs and tissues were dissected and weighed; the radioactivity of each sample was detected by r-counter; injection dose percentage per gram tissue (%ID/g) was calculated and the biodistribution obtained. Both MAGS conjugated oligonucleotides DNAs and natural oligonucleotides DNAs have the same hybridization activities. The whole body images demonstrate improved targeting of antisense DNAs vs sense DNAs in the KB-G2 but not the KB-31 animals. Tumor levels in the KB-G2 animals were significantly higher for the antisense DNAs vs sense DNAs (14.7 vs 8.5% ID/g) while this difference (8.6 vs 4.3% ID/g) was insignificant in the KB-31 animals. Evidence for tumor targeting in vivo by an antisense in that mechanism has been obtained; statistically higher tumor accumulations of the 99mTc-antisense DNA were observed when compared to the control 99mTc-sense DNA. The successful localization of antisense DNA in tumor demonstrates that antisense tumor targeting in vivo is feasible even though improvement in tumor delivery and normal tissue clearance are needed for practical antisense imaging.